The honey bees in America and in Europe are various races of Apis mellifera. Other related species worldwide used for honey production include Apis cerana, Apis dorsata and Apis florea. There are numerous diseases threatening honey bee families, and thus their honey production. These diseases arise from many sources, including bacteria, fungi, protozoa and mites. The ones responsible for the greatest economic losses are: Foulbrood-American and European (bacteria), Chalkbrood (fungus), Nosema (protozoan), and Varroa (mite).
American Foulbrood, which is found on every continent, is caused by the spores of the bacterium Bacillus larvae, which can remain viable indefinitely on beekeeping equipment. It infects the gut of worker, drone and queen larvae and, while it may not destroy a colony in the first year, if left unchecked may ultimately lead to the death of the colony. The main method of treatment is with the antibiotic oxytetracycline, administered in various forms with a sugar carrier. However, there are many problems associated with administration of oxytetracycline, including problems related to stability, antibiotic contamination of the honey, the possibility of killing open brood on the face of brood combs, and unevenness of dosing. European Foulbrood disease is caused by the bacterium Melissococcus pluton, which is fed to the worker, drone and queen larvae by nurse bees. Diseased colonies fail to increase normally so that no surplus honey, in excess of that needed by the colony to survive, is available for the beekeeper. Oxytetracycline is also used for treating such diseased colonies, but the most efficient dosing system for treating American Foulbrood, using Extender Patties, does not work well for this disease.
Chalkbrood disease is caused by the fungus Ascosphaera apis, which primarily infects larvae of workers and drones. Infected larvae become overgrown with a white cotton-like mycelium and eventually dry to a hard, white or gray shrunken mass (thus the name Chalkbrood) referred to as a mummy. The fruit-bodies of the fungus develop on the gray-colored mummies, and the spores released from the spore capsules can enter the air of the beehive. This prompts repeated infection of the developing brood through feeding by the cleaning bees. As a result of infection, the colonies fail to grow to a sufficiently large size, their resistance becomes impaired and their honey-producing capacity decreases to a degree depending on the severity of the mycotic infection. The disease is prevalent in the entire temperate zone, spreading apparently from southeastern Europe westward. Massive outbreaks have occurred since 1990 in Hungary, where infection rates of 90-100% are common in certain apiaries. There, the infected bee colonies were not able to produce enough honey, and on many occasions beekeepers found empty hives. No chemotherapeutic agent is available for the control of this disease. Chlorine gas has been investigated, but it fails to kill the spores. The most promising approach to control Chalkbrood is to maintain populous colonies to make up for losses in honey, as well as to use stocks that show evidence of resistance to the organism. A related infection, Stonebrood disease (forming stone-hard larvae) is caused by the fungus Aspergillus flavus and related species. These are common organisms, and difficult to eliminate.
While the above bacterial and fungal diseases affect the larvae of honey bees, the protozoan Nosema disease, caused by the microsporidian Nosema apis Zander, is by far the most widespread of the adult honey bee diseases. The symptoms of Nosema disease are often confused with other causes, and infect individual honey bee workers in many ways. The life span of infected bees is reduced, and can fall to 22%-44% of normal. Also the infected nurse bees are less able to feed brood. Honey bee death rates exceed birth rates, leading to reduced nectar collection and depressed honey yields. Fumigation of empty hives with ethylene oxide and acetic acid has been used to reduce contamination, as has thermal sterilization of hive equipment. The only chemotherapeutic agent that has shown some success, of the many tested, is fumagillin, administered in a sugar syrup.
Bees are attacked by a number of viruses, causing such conditions as Sacbrood Disease and paralysis. These viral diseases are generally not treated, but also do not pose a significant economic threat.
The parasitic honey bee mites Acarapis woodi (Acariosis) and Varroa jacobsoni (Varroasis), which are found on every continent except Australia, also affect adult honey bees. The mites are difficult to detect, and their discovery in 1921 and the concern over the potential impact on beekeeping in the United States led to enactment of the Honeybee Act of 1922, which restricted the importation of honey bees from countries where the mites were known to exist. When over 30% of the bees in a colony becomes parasitized with mites, honey production is reduced, as is the likelihood of winter survival.
The deficiency of reliable treatments for many of these diseases, affecting both bee larvae and adults is a major problem. A significant improvement in the survival of bee larvae and the extension of the life span of adult bees would be of great value to the beekeeping industry, allowing more bees to make more trips to gather nectar, pollen, water and propolis, thus ensuring greater honey production.
Accordingly, there is a need in the art for improved compositions and methods for controlling and treating infections in honey bees, such as Foulbrood and Chalkbrood Diseases. The present invention fulfills these needs and provides further related advantages.